1. Field of the Invention
The present invention relates to an optical connector including an optical waveguide for transmitting optical signals and a ferrule for optical connection provided at each end of the optical waveguide, and a method of manufacturing the same.
2. Description of the Related Art
In recent years, an optical interconnection technique which employs flexible polymer optical waveguides for connection between electronic devices and between boards in the devices has been used in place of conventional electrical interconnections.
FIG. 16 shows exemplary optical connectors used for coupling between optical interconnect lines as described above.
Each of the optical connectors shown in FIG. 16 includes an optical connection terminal of a predetermined shape known as a ferrule 100 which is mounted to a longitudinal end portion of a strip-shaped optical waveguide (optical waveguide section) 104. This optical connection ferrule 100 is provided with an optical waveguide fixing through hole or recessed groove. When the strip-shaped optical waveguide 104 inserted into an insertion opening of the through hole on one side is fixed therein, one longitudinal end surface (an optical connection surface) 104a of the strip-shaped optical waveguide 104 is visible or revealed from an exit opening of the through hole on the other side which is provided in a front end surface (coupling surface) 100a of the ferrule 100, and the end surface 104a of the strip-shaped optical waveguide 104 and the end surface 100a of the ferrule 100 are flush with each other, as disclosed in Japanese Published Patent Applications Nos. 2002-40298, 2006-39282, and 2008-191187.
In such an optical connector, guide holes 100b (alignment means) for receiving alignment guide pins 101 therein are provided in predetermined positions of the front end surface (coupling surface) 100a of the ferrule 100. The guide holes 100b are used to establish connection between the optical connectors. Specifically, opposite ends of the guide pins 101 are inserted into the guide holes 100b of two ferrules 100 placed so that the front end surfaces 100a of the respective ferrules 100 are in face-to-face relation with (or opposed to) each other, and the front end surfaces 100a of the respective ferrules 100 are butt-joined to each other. This brings the longitudinal end surfaces (optical connection surfaces) 104a of the respective strip-shaped optical waveguides 104 fixed in the through holes of the two ferrules 100 into abutment with each other, to establish optical connection between the strip-shaped optical waveguides 104. The optical connectors joined together in this manner are prevented from becoming disengaged and are retained by a fastening member, such as a clamp spring 102 and a locking member, prepared separately.
The use of optical interconnection employing optical connectors around CPUs in boards of devices and around chips has started. Around the chips, there is limited space and a large number of optical connectors are used. It has therefore been contemplated to reduce the size and costs of optical connectors as described above.
It is, however, conventional common technical practice to establish connection between strip-shaped optical waveguides by the use of optical connectors including ferrules, as disclosed in Japanese Published Patent Applications Nos. 2002-40298, 2006-39282, and 2008-191187. There are limits to the reduction in the size of optical connectors. An attempt to reduce the size of optical connectors beyond the limits is considered to result in the lowered accuracy of optical connection.
In a conventional optical connector, it is difficult to align a strip-shaped optical waveguide in its proper position within a ferrule when the ferrule is assembled to an end of the optical waveguide. Misalignment resulting from the aforementioned difficulties might cause a drawback such that significant coupling losses are produced when optical waveguides are connected together.